A cellular mobile communication system generally has a plurality of base stations (eNB) dispersed across a geographic service area to provide services to multiple user equipment (UE). To provide high data rates, smart antenna technology, named as multiple-input-multiple-output (MIMO), has been adopted in many wireless systems, such as IEEE 802.11n, Worldwide Interoperability for Microwave Access (WiMAX) and Long Term Evolution (LTE). In these MIMO systems, eNBs and UEs are equipped with multiple transmit/receive antennas and utilize spatial diversity or multiplexing gains to maximize system capacity.
Practical implementation of a MIMO system is a complex process since it is difficult to choose a MIMO mode best suited for a specific transmitter and receiver, given various environments and time-varying channels. Additionally, an initially determined MIMO mode may no longer be optimal when certain environmental variables change, such as the speed of the UEs, the SNR of the UEs, and other variables.